We have an existing Cognos BI version 10.1.1 (FP1 is installed as well) installation and are starting to evaluate version 10.2. Can 10.2 be an in-place upgrade (i.e., over the existing 10.1.1 installation), or does 10.2 have to be a separate installation (i.e., either uninstall 10.1.1 first then install 10.2 and use the existing content store, or install 10.2 to a separate directory and have a new content store for it as well)?

I would guess it would have to be a separate install. Even 10.1.1 had to be a full re-install over 10.1.0. This is not like a fix pack. You could really have a problem if you install in the same directories.

On the other hand you can install on the same servers/platforms as long as you use different directories for the installation. Also create an alternate web server install. I use IIS so this was fairly simple. After cutover I just pointed the 8.3 url to the 10.1 virtual directories so users could not use the old version.

I did this for my 8.3 to 10.1 upgrade where I had both running on the same group of servers for a while for the final step of production testing and working all reporting bugs out due to depreciated features that still worked in 8.3. At final cut-over I had to export and import the final 8.3 content store. I had previously exported all my fixed reports and then just re-imported them.